Loader linkage



Dec. 24, 1968 s. E. SMELCER 3,417,891

LOADER LINKAGE Filed July 19, 1967 2 Sheets-Sheet 1 INVENTOR GLEN E. SMELCER BY 7 5M ATT'Y.

Dec. 24, 1968 s. E. SMELCER LOADER LINKAGE 2 Sheets-Sheet 2 Filed July 19, 1967 INVENTOR GLEN E. SMELCER ATT'Y United States Patent 3,417,891 LOADER LINKAGE Glen E. Smelcer, Hinsdale, Ill., assignor to International Harvester Company, Chicago, 111., a corporation of Delaware Filed July 19, 1967, Ser. No. 654,403 Claims. (Cl. 214-778) ABSTRACT OF THE DISCLOSURE A front end loader linkage for use with a prime mover. The linkage has a jointed boom with a cam and lock device to provide either standard loader operation with the cam disengaged and lock engaged, or high lift operation with the lock disengaged and the cam operable to pivot the front section of the boom to a higher position when the back section of the boom is raised.

Background of the invention Among the design objectives in the loader field are those of providing a physical configuration in which the loader bucket or load carrying tool is as close as possible to the front wheels of the loader while obtaining a maximum lift height for unloading the bucket into high walled trucks and the like. This provides the stability and breakaway lift capacity necessary when the bucket is in its lowermost position while still allowing the highest lift for dumping.

The foregoing objectives have commonly been provided in the loader field by utilizing a downwardly curving boom; however, with this arrangement the lift cylinder must raise the boom to an extreme height to provide the necessary lift for the bucket dump. This therefore necessitates a long and expensive lift cylinder which requires more fluid volume for operation as compared to smaller units.

Summary of the invention This invention relates to a loader linkage for mounting on the forward end of a prime mover to provide high bucket lift while maintaining good loader stability. The invention relates more pasticularly to an articulated boom assembly and camming arrangement which positions the bucket close to the front tractor wheels when the bucket is at ground level while achieving an optimum bucket height when the boom is elevated.

The present invention provides a loader linkage wherein the lifting cylinder is smaller and of shorter extended length as compared to conventional designs, thus providing a more compact mechanism. The cylinder is also less likely to buckle when fully extended because of its shorter length.

It is an object of the present invention to provide a loader linkage having a jointed boom in which a cam moves the front of the boom upward to achieve additional bucket height as the rear of the boom is raised.

Another object is to provide a retractable camming mechanism and lock for the above described jointed boom assembly in which, with the cam retracted and the lock engaged, the boom assembly may be operated as a rigid, conventional boom.

Brief description of the drawing Other objects and advantages will become readily apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of the loader linkage showing the jointed boom construction;

FIGURE 2 is a side view of the loader linkage con- Patented Dec. 24, 1968 ice nected to the forward end of a tractor, with the bucket in its lowered position;

FIGURE 3 is a side view similar to FIGURE 2, with the bucket in its raised position;

FIGURE 4 is an enlarged sectional view of a component element of the invention taken along the line 44 of FIGURE 2; and

FIGURE 5 is a enlarged side view of another component element of the invention.

Description of the preferred embodiment Referring now to the drawings, FIGURE 1 shows a perspective of the preferred loader linkage including a pair of jointed booms 11 attached to a prime mover 10. The booms are identical and it will be sufiicient to describe only the right boom shown in FIGURES 2 and 3. The boom 11 includes a proximate or rear boom section 12 and an extension or forward boom section 13. The rear boom section is pivotally connected at one end to the prime mover 10 at 14. The other end of boom section 12 is pivotally connected at 15 to arcuate forward boom section 13. Forward section 13 comprises a rear segment 13A and a front segment 13B. A bucket or load carrying tool 16 is pivotally connected at 18 to the forward end of segment 13B.

A lift cylinder 23 is pivotally connected at one end 24 to rear boom 12 and at the other end 25 to the prime mover for raising and lowering the boom. A tilt cylinder 26 is pivotally connected at one end 28 to front boom segment 13B and at the other end 29 to the bucket or load carrying tool 16.

A conventional hydraulic circuit (not shown) is provide to operate both lift cylinder 23 and tilt cylinder 26.

A retractable camming device or reaction member 30 is located on the forward end of prime mover 10. This camming device includes a hydraulic cylinder 31 and a plunger rod 32. The operator may selectively extend or retract rod 32 by energizing cylinder 31 through a conventional hydraulic control circuit (not shown). When rod 32 is extended it moves into slot 33 in the rear boom portion 12 and bears against the top side of forward boom section 13A throughout pivotal movement of boom 11. A stop member 34 is secured on the inside of rear boom section 12 and provides a rigid support for forward boom portion 13 when plunger rod 32 is disengaged from boom segment 13A. A stop 35 is attached to rear boom section 12 to contact forward boom section 13 when the boom reaches its highest position as shown in FIG- URE 3. This prevents the boom from moving to an unstable over-center position.

The invention further incorporates locking mechanism 36 which comprises support member 37 movable on rear boom section 12 and a bottom brace 38 attached to member 37 and extending under segment 13A of forward boom section 13. When lock 36 is in its rearward position (phantom line of FIGURE 5) the lock is disengaged from the front boom section 13. The operator may slide mechanism 36 forward (solid line of FIGURE 5) until the lock 36 retains the front boom section 13 in a fixed position relative to the rear boom section 12. This provides a rigid boom which will operate as a conventional loader. Rod 32 is retracted by the operator whenever lock 36 is in its forward position to allow upward movement of rear boom section 12. A lock positioning apparatus may be provided to retain lock 36 in either its rearward or forward position. In the preferred embodiment this comprises a flat spring 40 which urges pin 41 into engagement with either of the holes 42 and 43 in the bottom of the rear boom section.

In operation, assuming bucket 16 is in its lowermost position, hydraulic fluid is applied to lift cylinder 23 to raise the boom and bucket 16. In one mode of operation rod 32 would be retracted with lock 36 engaged to efiect a rigid loader linkage which would function as a conventional loader. In another mode rod 32 would be extended with lock 36 disengaged. As rear boom section 12 is raised rod 32 will cam against rear boom segment 13A, thus pivoting front segment 13B upwardly. Stop 35 will contact the front of segment 13B to limit the maximum lift position for the boom.

What is claimed is:

1. A jointed boom for supporting a load carrying tool on a prime mover, the boom comprising the combination of: a rear boom section having one end pivotally attached to the prime mover; a front boom section having front and rear segments, the front section being pivotally attached to the free end of the rear section intermediate the segments, the tool being mounted on the front segment; means to raise and lower the boom; and cam means on the prime mover to react against the rear segment as the boom is raised to pivot the front segment upwardly relative to the rear boom section.

2. The invention as described in claim 1 wherein the cam means comprises a reaction member selectively movable into and out of camming relationship with the rear segment.

3. The invention as described in claim 1 and further including first lock means attached to the rear boom section to operatively contact the forward edge of the rear segment when the bucket is at its uppermost position.

4. The invention as described in claim 2 and further including second lock means to secure together the front and rear boom sections whereby the boom may be raised as a rigid unit when the cam means is out of contact with the rear segment.

5. The invention as described in claim 4 wherein the second lock means includes a lock member slidable'on the rear boom section between a rear position disengaged from said front boom section and a forward position in locking engagement with the front boom section.

References Cited UNITED STATES PATENTS 3,370,729 2/1968 Clarke 214-770 HUGO O. SCHULZ, Primary Examiner.

US. Cl. X.R. 214145 

